1. Field of the Invention
The present invention relates to an improved system and process for the loading and hot gas regeneration of adsorbent beds which are used in the purification of liquids such as tertiary butyl alcohol and the like.
2. Description of the Prior Art
Liquids such as tertiary butyl alcohol and the like are treated in order to remove impurities by passing the liquid through a bed of suitable solid adsorbent particles. When the maximum contaminant adsorption or loading is reached, the adsorbent bed can be regenerated by draining liquid from the bed and then stripping the contaminants into a stream of hot gas such as nitrogen.
For continuous operation it is advantageous to operate with two adsorbent beds in parallel with one bed being used to adsorb contaminants from the liquid being treated while at the same time the second bed is being regenerated.
A problem arises during the changeover where the bed which has reached its desired capacity to remove contaminants is to be regenerated and the bed which has been regenerated is to be placed in service to remove contaminants from the liquid being treated.
The bed which has reached its capacity and which is to be regenerated is drained of liquid with an inert gas such as nitrogen being provided to replace the drained liquid while the bed of regenerated adsorbent is filled with liquid and inert gas is vented therefrom.
Significant expenses are incurred as a result of venting the inert gases as an increased load is placed on a plant contaminated gas handling system, as well as the cost of replacing the vented inert gas.
The present invention relates to an improved method and system for carrying out parallel bed adsorption and regeneration while substantially avoiding the disadvantages of the prior art.
In accordance with the invention parallel adsorption beds are provided with connecting means such that under normal operation a liquid to be treated is passed through one bed while separately the second bed is being purged with a heated inert gas, and during the changeover period while the regenerated bed is filling with liquid to be treated, inert gas is displaced and passes to the depleted bed which is being drained preparatory to regeneration.